A Drug Enforcement Administration (DEA) judge has denied a motion to remove the agency from its role in an upcoming marijuana rescheduling hearing—though he sharply criticized responses from DEA and a prohibitionist group over an allegation that they unlawfully communicated during the cannabis rulemaking process.

With the initial rescheduling hearing set for next week, DEA Administrative Law Judge (ALJ) John Mulrooney has been addressing multiple motions from interested parties, largely centering around witness participation in the proceedings.

But one motion from two designated participants—Hemp for Victory and Village Farms International—made an especially bold assertion: It alleged DEA...